raco setup: fix problem with doc index database

When a tag is serializable but not `write'--`read' invariant,
then it needs to be serialized and deserialized.

Also, clarify and check in `tag?' that a tag should be
serializable.
Minor doc fix
Refactor to use syntax/id-table
Fix tests where type variable scoping is wrong
Simplify expansion of `pdefine:` and `define:`
Fix unsound type variable scoping

Closes PR 13123
Rackety
Explain scope of type variables in docs
Fix documented name of `unsafe-cons-list`
Documentation example for string-copy.
syntax-local-get-shadower: fix interaction with marked bindings

Getting a shadower should not drop module context if the context
determines a binding that has marks.
Fix missing set-integer-set-contents!

Closes PR 13368

This was a MzScheme -> Racket transition issue. Also
added tests and fixed some docs as well.
Make integer-sets implement generic interfaces

Supports gen:stream, gen:equal+hash, gen:custom-write
improve the performance of typing a close paren
Initial commit for `typed/plot' module

I also made some minor changes to `plot' so that its functions would
type more easily. In particular, everything that used to take a list
of vectors now accepts a (Sequenceof (Sequenceof Real)). The 3D
discrete histogram renderers now also accept lists as well as vectors
in the sequence of categories.

For now, in typed/plot functions, optional non-keyword arguments are
required. As soon as Vincent closes PR 13354, I should be able to
uncomment part of a macro in "typed/plot/syntax.rkt" to make them
correctly optional.
make scheme_check_threads() run at least on thread quantum

As long as some thread is ready to run, and in case the threads
synchronize after very little work, keep checking threads for
at least one thread quantum.
date struct: improve docs

Closes PR 13371
fix docs on scheme_malloc_fail_ok

Closes PR 13363
fix doc typo

Closes PR 13362
fix optimizer bug

Moving an expression that is referenced through a level of copy
propagation did not fix up a nested static distance correctly.

Closes PR 13355